Previous studies indicate that cell-mediated immunity (CMI) plays a significant role in the pathophysiology of periodontal disease. These studies have measured varied cell-mediated immune responses of peripheral blood leukocytes to dental plaque antigen. It appears that the distribution of the local gingival leukocyte population is different from that found in peripheral blood. Additionally, the local gingival environment is rich in factors that are known to modify cell-mediated immunity and leukocyte to leukocyte interaction. Therefore, the response of gingival crevice leukocytes to plaque antigens may be significantly different from that mediated by peripheral blood leukocytes. Similarly, gingival crevice leukocytes may be susceptible to serum elements which can modify CMI. The objectives of the proposed study are to compare the immune characteristics and functional relationships of gingival crevice leukocytes with peripheral blood leukocytes. Populations of gingival crevice and peripheral blood leukocytes will be studied for metabolic activity in patients with known neutrophil and periodontal abnormalities and activity will be correlated with level of disease. Immune complexes of known composition will be tested for their ability to modify both gingival crevice and peripheral blood leukocyte function and for their ability to effect leukocyte interactions. Modification of lymphocyte function by plaque and antigen activated neutrophils will be studied for populations of gingival crevice and peripheral blood cells. The functional effect of neutrophils on lymphocytes will be examined and the chemical nature of neutrophil-derived lymphocyte activators will be determined. The concentration of activating factors in the gingival crevice will be quantified as will the ability of gingival crevice leukocytes to produce such a factor.